The invention relates to a circular knitting machine with a circular knitting unit fitted with needles and an expander arranged under the circular knitting unit for the tubular knit formed by the circular knitting unit. The expander is rotatably mounted on a central rod arranged coaxially to a knitting machine central axis.
With the expander the tubular knit is formed into a double-layered web laid flat and is then withdrawn and wound up. In this process the knitted fabric exerts considerable forces on the expander. These forces are transferred to the central rod, which can thus result in fatigue fractures of the central rod. Moreover, the forces also can result in folding and ringing of the knitted fabric during winding, which makes further processing difficult.
To remedy this problem document DE 12 28 021 has proposed to suspend the expander on the machine on chains. However, this type of suspension of the expander can lead to a relatively substantial lateral displacement of the expander as a result of the forces exerted by the tubular knit. The lateral displacement makes it difficult to uniformly withdraw and wind up the web.
DE 24 43 067 describes an expander with articulated straps, which are connected to a rigid expander frame by a damper unit. The damper units absorb part of the forces exerted by the tubular knit. This solution, however, is structurally complicated. The damper units suffer fatigue over time and must be regularly replaced.
DE 31 12 181 also discloses expanders with different adjustment possibilities of individual expander parts relative to one another to enable forces exerted by the knitted fabric to be compensated. These solutions, however, also are very complicated structurally.